Use llvm::sys::Path to implement "mkdir -p".

Change-Id: I3bb36e1a8050bbd9744fd02935b6186d2f285015
diff --git a/slang_utils.h b/slang_utils.h
new file mode 100644
index 0000000..7fe5aac
--- /dev/null
+++ b/slang_utils.h
@@ -0,0 +1,22 @@
+#ifndef _SLANG_COMPILER_UTILS_H
+#define _SLANG_COMPILER_UTILS_H
+
+#include <string>
+
+namespace llvm {
+  class StringRef;
+}
+
+namespace slang {
+
+class SlangUtils {
+ private:
+  SlangUtils() {}
+
+ public:
+  static bool CreateDirectoryWithParents(llvm::StringRef Dir,
+                                         std::string* Error);
+};
+}
+
+#endif  // _SLANG_COMPILER_UTILS_H